Pigment compositions of a diketopyrrolopyrrole and an aminoalkyl acrylate resin

ABSTRACT

A pigment composition comprising 
     A) a 1,4-diketopyrrolo 3,4-c!pyrrole pigment of formula ##STR1## wherein A and B are each independently of the other a group of formula ##STR2## wherein R 1  and R 2  are each independently of the other hydrogen, halogen or CN, and 
     B) 0.1-20% by weight, based on the diketopyrrolopyrrole of formula I, of an acrylic resin obtainable by homopolymerisation of a monomer of formula ##STR3##  wherein R 3  is hydrogen or methyl and R 4  and R 5  are each independently of the other hydrogen, methyl or ethyl, and n is an integer from 1 to 6, or by copolymerisation of the same monomer with a monomer which is copolymerisable with said same monomer, wherein the homopolymerization or copolymerization is carded out in the absence of a nonionic active agent 
     These pigment compositions have excellent rheology and the colorations obtained with them have surprisisingly high gloss.

This is a continuation-in-part of application Ser. No. 08/346,113, filed on Nov. 29 1994 abandoned.

The present invention relates to a pigment composition comprising a diketopyrrolopyrrole pigment and an aminoalkyl acrylate, and to the use of said composition for colouring organic material of high molecular weight.

Various publications teach that specific properties of pigments, including also diketopyrrolopyrroles, can be enhanced by treatment with analogous, slightly modified products and/or resins. U.S. Pat. No. 4,791,204 discloses, inter alia, pigment compositions comprising a diketopyrrolopyrrole pigment and a metal or ammonium salt of a sulfonated diketopyrrolopyrrole. These compositions have excellent theology and the colorations obtained therewith exhibit high gloss. Similar results are obtained in US patent 5,200,528 with pigment compositions comprising a diketopyrrolopyrrole pigment and a diketopyrrolopyrrole containing at least one aminoalkoxy radical. U.S. Pat. No. 4,880,472 discloses organic pigments, including also diketopyrrolopyrrole pigments, the particles of which are provided with a tenacious coating of metal oxides fixed by an interlayer that contains hydroxyl groups, which pigments are likewise distinguished by very good theology. Such pigment compositions are also very suitable for the warp-free pigmenting of polyolefins. EP-A 466 646 discloses a process for the warp-free pigmenting of polyolefins, which comprises coating the surface of the pigment particles, e.g. a diketopyrrolopyrrole, direct or indirect with a layer of a polar polymer, e.g. an acrylic polymer based on acrylic acid, methacrylic acid and/or alkyl esters thereof. In this process, the acrylic polymer layer is preferably applied to a silane layer which in turn is adsorbed on to a layer of hydrolysed zirconium acetylacetonate coating the surface of the pigment particles. U.S. Pat. No. 4,734,137 discloses a process for the preparation of azo, thioindigo and, in particular, quinacridone pigments having good theology and superior gloss, which comprises dissolving one of said pigments in an aprotic polar solvent in the presence of an alkali metal hydroxide and water and then precipitating a pigment preparation by addition of an aqueous acidic solution of an aminoalkyl acrylate resin which, after isolation by standard methods, has the desired properties. A similar pigment preparation containing an anionic surfactant is disclosed in JP-AO 58-215 461.

It has now been found that the treatment of specific diketopyrrolopyrrole pigments with an aminoalkyl acrylate resin results in quite unexpectedly superior properties, especially as regards gloss and theology.

Accordingly, the invention relates to a pigment composition comprising

A) a 1,4-diketopyrrolo 3,4-c!pyrrole pigment of formula ##STR4## wherein A and B are each independently of the other a group of formula ##STR5## wherein R₁ and R₂ are each independently of the other hydrogen, halogen or CN, and

B) 0.1-20% by weight, based on the diketopyrrolopyrrole of formula I, of an acrylic resin obtainable by homopolymerisation of a monomer of formula ##STR6## wherein R₃ is hydrogen or methyl and R₄ and R₅ are each independently of the other hydrogen, methyl or ethyl, and n is an integer from 1 to 6, or by copolymerisation of the same monomer with a monomer which is copolymerisable with said same monomer, wherein the homopolymerization or copolymerization is carried out in the absence of a nonionic active agent.

R₁ und R₂ defined as halogen will be taken to mean iodo, fluoro, preferably bromo and, most preferably, chloro.

In the diketopyrrolopyrrole pigment of formula I, A and B are preferably identical and are preferably a group of formula ##STR7## wherein R₁ is hydrogen, chloro or phenyl.

Particularly preferred pigment compositions of this invention are those which contain an acrylic resin B which is obtained by homopolymerisation of a monomer of formula II, wherein R₃, R₄ and R₅ are methyl and n is 1 or 2, in an amount of 3-10% by weight, based on the diketopyrrolopyrrole of formula I.

The pigment compositions of this invention can be prepared in simple manner, typically by aftertreating the pigment in aqueous suspension with the acrylic resin, with stirring. A start can be made from the pretreated dry pigment powder, a filter cake or from a suspension resulting from the treatment. The acrylic resin can either be dissolved beforehand in water or added in solid form to the pigment suspension.

If necessary, the suspension can be dispersed by conventional methods using e.g. a high-pressure homogeniser or a high-speed impeller. Usually this is not necessary, as the acrylic resins normally have very good wetting properties. The content of pigment in the suspension may vary over a wide range and can be up to 40% by weight. It is expedient to use suspensions having a pigment content of 5 to 20% by weight. The aftertreatment of the pigment with the acrylic resin (B) can be carried out at room temperature, but in some cases also at up to elevated temperature of c. 80° C. The stirring time varies from 1 to 20 hours. To facilitate the filtration of the treated pigment, it is also possible to use a filter aid such as 0.5 to 15% by weight of an aliphatic 1,2-dihydroxy compound containing 8 to 22 carbon atoms, preferably 1 to 5% by weight of 1,2-dodecanediol, provided this does not adversely affect the use of the inventive pigment compositions. Analogous ingredients (e.g. customary dispersants) may also be added in usual amounts to enhance the dispersibility of the product.

The acrylic resin (B) is known and can be prepared by conventional methods, e.g. as described in U.S. Pat. No. 4,734,137.

The pigment compositions of this invention can be used as pigments for colouring organic material of high molecular weight.

Illustrative examples of organic materials of high molecular weight which can be coloured with the novel pigment compositions are cellulose ethers and esters, typically ethyl cellulose, nitrocellulose, cellulose acetate, cellulose butyrate, natural resins or synthetic resins, typically polymerisation or condensation resins, such as aminoplasts, preferably urea/formaldehyde and melamine/formaldehyde resins, alkyd resins, phenolic plastics, polycarbonates, polyolefins, polystyrene, polyvinyl chloride, polytetrafluoroethylene, polyamides, polyurethanes, polyesters, polyether ketones, polyphenylene oxides, rubber, casein, silicone and silicone resins, singly or in mixtures.

The above high molecular weight organic compounds may be singly or as mixtures in the form of plastics, melts or of spinning solutions, paints, coating materials or printing inks. Depending on the end use requirement, it is expedient to use the pigment compositions of the invention as toners or in the form of preparations. The pigment compositions of the invention can be used in an mount of 0.01 to 30% by weight, preferably 0.1 to 10% by weight, based on the high molecular weight organic material.

For pigmenting paints, coating materials and printing inks, the high molecular weight organic materials and the pigment compositions of the invention, together with optional additives such as fillers, other pigments, siccatives or plasticisers, are finely dispersed or dissolved in a common organic solvent or solvent mixture. The procedure may be such that the individual components by themselves, or also several jointly, are dispersed or dissolved in the solvent and thereafter all the components are mixed.

The colorations obtained in plastics, fibres, paint systems or printing inks have good allround fastness properties such as superior colour strength, good dispersibility, good fastness to overspraying, migration, heat, light and weathering, and they have low viscosity.

Furthermore, compared with unmodified base pigments and also with the treated pigments of the prior art, the novel pigment compositions have enhanced performance properties in application, such as enhanced rheology and shelf life, lesser separation effects, such as floating when concurrently using e.g. white pigments, a lesser tendency to flocculate, and unexpectedly high gloss. Owing to the good rheological properties of these compositions it is also possible to prepare coating materials and paints systems with high loading. They are therefore preferably suitable for colouring paints, especially for metal effect finishes.

The invention is illustrated by the following Examples.

EXAMPLE 1a

To a solution of 10 g of dimethylaminoethyl methacrylate in 30 g of water is added 0.1 g of K₂ S₂ O₈ (1% by weight of initiator, based on the monomer). The solution is repeatedly degassed, flushed with nitrogen and stirred for 5 hours at 30° C. under nitrogen. The solution is thereafter diluted with 40 ml of water. A highly viscous substance initially forms, but liquifies again.

b) 27.2 g of a 36.8% aqueous falter cake of 1,4-diketo-3,6-diphenylpyrrolo 3,4-c!pyrrole are dispersed in 65 g of water with 7.7 g of the polymer solution a) by efficient stirring at room temperature for 5 hours. This corresponds to a polymer concentration of 10% by weight, based on the pigment. The suspension is subsequently filtered and the residue is washed with water, dried at 80° C. and pulverised.

EXAMPLE 2

Example 1 is repeated, with the sole exception that 4% instead of 1% of the initiator K₂ S₂ O₈ is used.

EXAMPLE 3

1051 g of a 28.54% aqueous filter cake of 1,4-diketo-3,6-bis(4-chlorophenyl)-pyrrolo 3,4-c!pyrrrole are dispersed with 67.6 g of a polymer solution according to Example 2 (i.e. obtained with 4% of initiator) in 1881 g of water (corresponding to a polymer concentration 5% by weight, based on the pigment). The suspension is further stirred overnight and then filtered. The residue is subsequently washed with water, dried in a vacuum shelf drier and pulverised.

EXAMPLE 4

Example 1 is repeated, with the sole exception that 1,4-diketo-3,6-diphenyl-pyrrolo 3,4-c!pyrrole is replaced with the same amount by weight of 1,4-diketo-3,6-bis(4-diphenyl)pyrrolo 3,4-c!pyrrole.

EXAMPLE 5

Example 1 is repeated, with the sole exception that the polymer is used in an amount coresponding to 10% by weight of polymer, based on the pigment.

EXAMPLE 6

2 g of the product obtained according to EXAMPLE 1b) and 48 g of a stoving lacquer comprising

56 g of alkyd resin ALKYDAL®F310 (Bayer AG; 60% in xylene)

13g of melamine resin CYMEL®327 (Cyanamid; 90% in butanol)

25 g of xylene

25 g of butanol

2.5 g of 1-methoxy-2-propanol and

1 g of silicone oil (1% in xylene)

are mixed by conventional methods. The resultant colour lake is drawn to a film on a glass plate. Before storing in a circulating air oven (30 minutes at 120° C.), the coating is allowed to dry in the air for c. 30 minutes at an inclination of 25°.

The gloss values are measured with a gloss meter (Zehntner ZGM 1020®) at an inclination of 20° according to DIN 67 530.

The finish so obtained has a gloss which is unexpectedly better than that of a finish obtained with an uncoated pigment.

Replacement of the product of Example 1b) with each of the products of Examples 2 to 5 gives comparable results.

EXAMPLE 7

To determine the flow properties, the products of Examples 1-5 as well as the corresponding untreated pigments are incorporated in conventional manner into an alkyd paint system (SETAL®84, Kunstharzfabrick Synthesis BV, Holland; solids content 70% by weight).

The flow properties of the mill base so obtained, which contains 12% by weight of pigment and 42% by weight of total solids and whose pigment/binder ratio is 0.3, are determined with a HAAKE ROTOVISCO®RV12 viscosimeter (measuring temperature: 25° C.; measuring system: SV-SP; shear rage: D=0-100 1/s!).

Compared with the mill bases obtained with untreated pigments, the mill bases obtained with the products of Examples 1-5 have markedly enhanced flow properties (viscosity values). 

What is claimed is:
 1. A pigment composition comprisingA) a 1,4-diketopyrrolo 3,4-c!pyrrole pigment of formula ##STR8## wherein A and B are each independently of the other a group of formula ##STR9## wherein R₁ and R₂ are each independently of the other hydrogen, halogen or CN, and B) 0.1-20% by weight, based on the diketopyrrolopyrrole of formula I, of an acrylic resin, obtained by solution homopolymerisation of a monomer of formula ##STR10## wherein R₃ is hydrogen or methyl and R₄ and R₅ are each independently of the other hydrogen, methyl or ethyl, and n is an integer from 1 to 6, or by solution copolymerisation of the same monomer with a monomer which is copolymerisable with said same monomer, wherein the homopolymerization or copolymerization is carried out in the absence of a nonionic active agent.
 2. A pigment composition according to claim 1, wherein A and B are identical in the 1,4-diketopyrrolo 3,4-c!pyrrole pigment of formula I.
 3. A pigment composition according to claim 2, wherein A and B are a group of formula ##STR11## wherein R₁ is hydrogen, chloro or phenyl.
 4. A pigment composition according to claim 1, which contains an acrylic resin B, which is obtained by solution homopolymerisation of a monomer of formula II, wherein R₃, R₄ and R₅ are methyl and n is 1 or 2, in an mount of 4-10% by weight, based on the diketopyrrolo-pyrrole of formula I.
 5. Organic material of high molecular weight coloured with a pigment composition as claimed in claim
 1. 6. Organic material of high molecular weight according to claim 5, which is a paint system or a printing ink. 